The present invention relates to a manufacturing method of oxide cathode for electron tube, and particularly, to a manufacturing method of oxide cathode for electron tube in which adding manner of scandium Sc or yttrium Y for extending the duration of ternary carbonate solid solution is improved and more excellent diffusing effects is obtained and thereby electron emitting characteristic is improved.
According to the prior art, heat treated scandium or yttrium is added to ternary carbonate solid solution in oxide state at predetermined rate, and this is made to mixed solution with pertinent adhesive agent (mainly nitro cellulose) and organic solvent (isoamyl acetate, alcohol etc.), and then this is ball milled and slurry is made, and this slurry is painted on the basic body metal (cap) by means of spraying or electric adhering, and thus a cathode is formed by melting said cap on a sleeve thereof. Electronic gun used said cathode is assembled and capped on tube, and process such as themo-dissolution and activation are passed through, whereby said slurry is used for the electron emitting material, at this moment, scandium or yttrium can be added to the slurry after ball milling of it, and it can also be used with other form (hydroxide nitrate etc.) other than oxide.
However, in case when scandium or yttrium is added by conventional method, since these scandium or yttrium is made to mix with ternary carbonate powder in powder state, mixture of uniform condition is hard to obtain, particularly in case when slurry is made by ball mill and then powder of scandium or yttrium is added to this, since there is worry that ternary carbonate crystal is broken, not only it is difficult to use ball milling method capable of obtaining sufficient diffusing effect, but since scandium or yttrium is added with small quantity, when sufficient diffusion is not obtained, there is disadvantage that it is hard to expect the improving effect of previously described duration characteristic and electron emitting characteristic.